1. Field of the Invention
This invention relates to a TV camera adapted to be attached to an eyepiece section of, for example, an endoscope.
2. Description of the Prior Art
A TV camera for an endoscope is known which is adapted to be attached to an eyepiece section of the endoscope with an image pickup element incorporated therein so that the body cavity of a human subject can be observed. A typical TV camera body for an endoscope includes a camera body with an image pickup element incorporated therein and the eyepiece section of the camera is mounted at the rear of the camera body for the operator to view the body cavity of a subject through the endoscope. A lens frame is mounted at the front portion of the camera body and equipped with a camera mount detachable from the eyepiece section of the endoscope. An image pickup optical system has a plurality of optical lenses and is mounted on a lens frame. A beam splitter is arranged behind the image pickup optical system to split light which has been incident thereto from the endoscope into a beam conducted to a receiving surface of an image pickup element and a beam conducted into a finder optical system which is coupled to the eyepiece section of the camera. Since the beam splitter for the finder is arranged at the rear of the image pickup optical system, the observation image of the endoscope is observed necessarily through the image pickup optical system and through finder optical system.
With the recent marked advance of the image pickup element, image pickup elements of excellent performance have been developed one after another, so that it is often necessary to replace the image pickup element of the one size with the image pickup element of another size. In order to replace an initially attached image pickup element with another new image pickup element of excellent perormance, it is necessary to replace the image pickup optical system so that a TV image or a finder image of a perperly matched size can be observed by the viewer. In the observation of the internal organs of a subject through the endoscope the operator views their image either through the eyepiece section of the endoscope or through the finder, i.e., from the eyepiece section of the camera. In this case it is desired that an image of the same size can be viewed through both the aforementioned eyepiece sections. When, therefore, the image pickup optical system is to be replaced on the typical TV camera for the endoscope, then it is necessary to make a design modification of all the the finder optical system.
As set forth above, in order to achieve this, it is necessary to re-design the TV camera substantially wholly, taking more time in design modification and an additional cost.